Vehicle safety braking system

ABSTRACT

This invention provides a safety arrangement for a dumping vehicle which may include a bumper movable to energize a brake actuator, the bumper being retractable upon tilting of the dumping bed. Modified bumper mounting arrangements are provided for various kinds of vehicles. A latching relay may be included to cause the brake actuator to hold the brakes locked, irrespective of disengagement of the obstruction. The bumper may include a pneumatic chamber with a flexible wall, with a pressure-operated switch for operating the brake actuator. Also, an exteriorly actuated switch may be used in a two-man operation in lieu of a bumper.

This is a division of application Ser. No. 646,287, filed Jan. 2, 1976.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a safety braking system.

2. Description of the Prior Art

Safety systems for vehicles sometimes have employed bumper elements forengaging an obstruction, frequently resulting in the sounding of thehorn or other audible warning. This has obvious shortcomings in that itrelies upon the reaction of the operation of the vehicle to the warningsignal for the application of the brakes. In U.S. Pat. No. 3,510,837 andin U.S. Pat. No. 3,923,330, the bumper element includes a means forapplying the brakes of the vehicle when an obstruction is encountered.Only the latter system is adaptable for a dump truck where it isnecessary to avoid engagement with the rear wheels of the vehicle or thesupporting surface beneath it when the bed of the truck is tilted.However, in that design the bumper mechanism merely bends and does notretract so that some portions of it can continue to extend downwardly atthe rearward of the truck.

None of the prior designs includes a means for continuing theapplication of the brakes after impact in the event that the bumpermechanism should be able to return to its original position.Consequently, there is never complete assurance of continued preventionof vehicle movement after the impact has occurred. Moreover, the priordesigns are not adapted for operation by a person stationed at therearward end of the vehicle as it moves, which means that the earliersystems are not operable until the obstruction has been engaged.Generally, the vehicle protection systems of the prior art have not beensuitable for locations at the forward or upper portions of a vehicle toprevent damage, for example, from engagement with an overhanging roof ora loading ramp.

SUMMARY OF THE INVENTION

The present invention provides an improved vehicle safety system whichavoids the shortcomings of the prior art and includes other advantages.The system may include a linkage positioned at the rearward end of adump truck with an impact member for moving the linkage to cause thebrakes to be applied when an obstruction is encountered. Included is ameans for automatic retraction of the linkage as the bed of the trucktilts when the load is to be dumped. The mechanism is generally in theform of a parallelogram linkage and retracts sufficiently to provideincreased clearance at the rearward end of the truck as the bed istilted.

The electrical circuit for the safety device may include a latchingrelay which will maintain the circuit to the solenoid for holding thebrakes in a locked condition even if the bumper element should return toits original position. Thus, once an obstruction is encountered thebrakes remain locked and can only be released by de-energizing thecircuit through overt action.

Various bumper mounting arrangements are provided which allow the systemto be utilized at various portions of the vehicle to prevent damage fromdifferent kinds of obstructions that may be encountered. In oneembodiment, no bumper element of any kind is used and instead there isprovided a normally closed switch positioned at the rearward end of thevehicle. This switch is in series with a source of power which causesenergization of a brake-actuating solenoid whenever the vehicle is putin reverse gear. This means that as soon as the vehicle is shifted intoreverse the brakes are locked. It can be driven rearwardly only when aman is positioned at the rearward end of a vehicle to hold the switchopen, thereby de-energizing the solenoid and releasing the brakes. Anykind of release of the switch again energizes the system to lock thebrakes. In this way the brakes may be locked from a remote position inadvance of any impact.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary side elevational view of a vehicle utilizing thesafety arrangement of this invention;

FIG. 2 is an end elevational view of the vehicle;

FIG. 3 is an enlarged fragmentary side elevational view of the bumpermechanism;

FIG. 4 is a diagram of the electrical circuit for the system;

FIG. 5 is a wiring diagram of an alternate circuit;

FIG. 6 is a fragmentary side elevational view of the vehicle with thebed in the tilted position;

FIG. 7 is a fragmentary view of an alternate bumper construction;

FIG. 8 is a sectional view of a bumper that provides an enclosed chamberin a pressure-operated device;

FIG. 9 shows a further modification of the bumper mounting; and

FIG. 10 is a side elevational view of a safety system operable from theexterior of the vehicle.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIGS. 1, 2 and 3, the system of this invention is associatedwith the rearward portion of a dump truck 10 where it is used to preventdamage during backing of the truck. The truck 10 includes a bed 11,pivotal relative to the chassis 13, about shafts 12 which are locatedimmediately behind the rear wheels 14. The system of this inventionincludes a transverse bumper 16 positioned beneath and immediatelybehind the bed 11 of the truck where it is carried by two parallel beams17 extending longitudinally of the truck 10. Forwardly of the bumper 16,on either side of the truck 10, are two spaced parallel normallyvertical support links 18 and 19. Each link 18 is at the forward end ofone of the beams 17 and includes parallel webs 20 welded to its bottomend that receive the beam 17 and are connected to it by a pivot pin 21.

Similarly, at the bottom end of each link 19, webs 24 are welded to aflat rod 25 that forms the lower portion of this link and straddle thebeam 17. A pivot pin 26 connects the webs 24 to the beam 17.

The link 19 includes a relatively short upper portion made up of a flatrod 28 to the lower end of which are welded webs 29. The latter elementsfit over the upper end of the flat rod 25 to which they are connected bya pivot pin 30. Thus, the two principal parts of the link 19 may pivotrelative to each other.

A flat plate 31 is welded, or otherwise suitably secured, to thehorizontal side rail 32 on either side of the truck bed 11 serving asthe means to attach the bumper and the support links to the truck. Pivotpins 34 and 35 connect the upper ends of the links 18 and 19,respectively, to the plate 31. One end of a tension spring 36 isanchored at a notch 37 in the upper edge of the plate 31, from which itextends downwardly and forwardly at an angle to engage an eyebolt 38extending through the forward link 18. This maintains the linkagenormally in the position shown in solid lines in FIGS. 1 and 3, with thelinks 18 and 19 in the vertical position, the beam 17 horizontal and thebumper element 16 positioned outwardly beyond the rearward end of thetruck.

Projecting outwardly from the flat plate 31 on at least one side of thevehicle is a bracket 39 which mounts a switch 40. The bracket 39 is atan angle relative to the horizontal and positions the plunger 41 of theswitch 40 normally in engagement with an angled tab 42 extending fromthe upper end of the forward link 18. The tab 42 has a downwardly bentlower part which is welded to the forward upper edge portion of the link18. Accordingly, the tab 42 will move with the link 18 upon rotation ofthat member about the pivot pin 34. Forward rotation of the link 18(clockwise as shown in FIGS. 1 and 3) will cause the tab 42 to move awayfrom the plunger 41 of the switch 40.

The system includes an additional switch 43 mounted on the chassis 13 ofthe vehicle, with its plunger 44 forcing upwardly. The lower surface 45of the bed 11 of the truck engages the plunger 44 when the bed is in itsnormal lowered position.

The switches 40 and 43 are incorporated in an electrical circuit shownin FIG. 4. In this circuit the switches 40 and 43 may be connected intothe existing back-up light circuit of the vehicle or a special circuitof this type may be provided. The back-up light circuit includes, inseries, the ignition switch 46 and a switch 47 which is closed when thetransmission of the vehicle is placed in reverse gear such as bymanipulation of gear shift lever 47a. When the ignition is on and thevehicle is in reverse, current will flow through the back-up light 48causing its illumination.

The switches 40 and 43 are connected to the back-up light circuit so asto be in parallel with the back-up light 48. These two switches are inseries with each other. Beyond and in series with the switches 40 and 43is a solenoid 49 connected to a brake actuator 50. The solenoid andbrake actuator are constructed such that when the solenoid 49 isenergized, the brake actuator 50 applies the brakes of the vehiclecausing it to stop. The actuator 50, in a pneumatic brake system, is avalve operated by the solenoid 49 to direct pressurized air to thebrakes.

The switch 43 is normally open, but is held closed when the truck bed 11is in the lowered position. The switch 40 is normally closed, but isheld open by the tab 42 at the upper end of the forward link 18.Accordingly, under ordinary conditions, when the ignition is on and thetransmission is in reverse, the switches 43, 44 and 45 are closed, butthe switch 40 is open. Therefore, no current flows to the solenoid 49and it has no influence on the braking system of the vehicle. However,if an obstruction, such as a parked vehicle 51, should be encountered bythe bumper 16, the switch 49 will be closed and the brakes applied tostop the vehicle before it can do damage to the obstruction or to thebacking vehicle.

This comes about through the movement of the linkage to the phantom lineposition of FIGS. 1 and 3. With the bumper 16 stopped by the obstruction51, it causes the horizontal beams 17 to move forwardly relative to thevehicle during the next increment of rearward movement of the vehicle.The links 18 and 19 pivot forwardly as this occurs. Such movement of oneof the links 18 causes the tab 42 at its upper end to move away from theplunger 41 of the switch 40. When this occurs, the switch 40 assumes itsnormally closed position, as a result of which the solenoid 49 isenergized and the brake actuator 50 is caused to apply the brakesinstantly. The vehicle then stops at once without allowing any damage tobe incurred. The brakes remain locked until the transmission has beenshifted out of reverse or the ignition is shut off, which willde-energize the solenoid 49.

If desired, a warning light 52 may be included in the brake actuatingcircuit, beyond the switches 40 and 43, to provide the driver with avisual indication when the system has been activated.

The brake actuating circuit also may be connected to the neutral safetyswitch 53 of the engine starting circuit. This switch will be closedwhen the transmission is in neutral, irrespective of whether or not theengine has been started. When the brake actuating circuit is connectedin series with the switch 53, it can protect against a runaway vehicleleft in neutral gear. The truck's brakes will be applied to bring it toa stop as soon as the bumper 16 encounters an obstruction. Diodes 54 and55 are included when the brake actuator is wired to the switch 53, toprevent reverse current flow.

When the truck bed 11 is tilted in dumping the load, rearward movementof the truck may be necessary. For this reason, the switch 43 opens whenthe bed tilts, de-energizing the circuit of the emergency brakingsystem.

The alternative circuit for actuating the brakes shown in FIG. 5utilizes a latching relay as well as the switches in controlling theflow of current to the solenoid that operates the brake actuator. Asshown in this circuit, the latching relay 57 is connected to the lead 58from the back-up light circuit, ahead of and in series with both thesolenoid 49 and the switches 40 and 43. Accordingly, if the bumperlinkage causes the impact switch 40 to be closed, current will flowthrough the latching relay 57, causing it to shift its position anddirect current to the solenoid 49 to operate the brake actuator 50 forlocking the wheels of the vehicle. The latching relay 57 will maintainthis position even if the switch 40 becomes opened again. There iscomplete assurance, therefore, that when the brakes of the vehicle havebeen applied no inadvertent release can take place. Only theinterruption of power to the latching relay from the input lead 58 willcause power to be removed from the solenoid 49 and release of the brakeactuator 50. Opening of the impact switch 40 will not interrupt the flowof current to the brake actuator.

The brake actuating mechanism is retracted when the bed of the truck istilted so that it does not interfere with movement of the tilting bedand does not become damaged as the bed is rotated. This is necessarybecause the rearward end of the truck bed moves downwardly as the bedpivots about the pivot shafts 12 and the brake actuating mechanism wouldstrike the supporting surface 59 beneath the vehicle or the rearwardwheels 14 if left in its original position. Retraction of the brakeactuating mechanism is very simply accomplished by a cable 60 on eitherside of the vehicle, attached by a pin 61 to the lower end portion ofthe rearward link 19, from where it extends forwardly and upwardly. Thecable 60 passes around a pulley 62 mounted on the side structure 32 ofthe truck bed then, going horizontally forward to a second pulley 63.From the latter pulley, which is ahead of the pivot shaft 12 of the bed11, the cable extends downwardly to an attaching element 64. Thissecures the cable to the chassis 13 beneath and slightly forwardly ofthe pulley 63. A tension spring 65 has a lower end anchored by theelement 64 and its other end 80 connected to the cable 60 adjacent thepulley 63. The force of the spring 65 normally provides slack in thecable 60 between the point of its attachment to the cable and the endconnection 64 for the cable. The length of the cable 60 between theupper spring end 66 and the attaching point 64 is approximately one andone-half times the length of the spring.

When the bed of the truck is tilted, as shown in FIG. 6, the end of thecable 60 attached by the element 64 remains fixed. The pulley 63, beingforward of the shaft 12, moves upwardly away from the fixed cable end.As a result, the cable 60 pulls on the link 19, thereby rotating theentire bumper mechanism forwardly and upwardly. This retracts the bumpermechanism so that it is inward of the rearward end of the vehicle andmoved upwardly to a position adjacent the bottom of the bed 11 of thetruck. In this position it is out of the way and does not interfere withthe rotation of the truck bed as it is tilted for dumping.

With the rearward link 19 made of two sections pivotally connectedtogether by the pin 30, there will be relative rotation of these twosections as soon as there is a pull from the cable 60. The result is animmediate raising of the outwardly extending bumper portion 16, assuringclearance beneath the bumper as soon as the bed of the truck is tilted.It is possible, however, to construct the rearward link 19 as a solidelement comparable to the front link 18, which is satisfactory for manyinstallations.

When the bed of the truck is lowered the mechanism returns to itsoriginal position as the pull on the cable 60 is released and the spring36 pulls the link 18 rearwardly and downwardly. The spring 38 thenmaintains the linkage in the solid line position of FIGS. 1 and 3,preventing it from experiencing unwanted movement during operation ofthe vehicle. Of course, when the bumper 16 encounters an obstruction thespring 38 readily yields in allowing the displacement of the bumper forclosing the impact switch 40.

The spring 65 acts as a safety device allowing extra movement of thecable 60 in the event some object should become lodged between thebumper 16 and the bed 11 of the truck. The spring 65 also canaccommodate variations in the installation position of the cable as maybe required for different vehicles.

FIG. 7 illustrates a bumper arrangement which may be used at differentlocations on a vehicle or which may be positioned at the rearward end ofa vehicle where retraction is not required. In this version, there is abumper element 67 mounted on a rod 68 that extends through a sleeve 69attached by a bracket 70 to the vehicle. Beyond the sleeve 69 a cam 71is carried by the rod 68 adjacent to a normally open switch 72 which iswired into the brake actuating mechanism at the same location as theswitch 40 described above. A compression spring 73 circumscribing therod 68 between the bumper element 67 and the sleeve 69 maintains thebumper element in a normally extended position. However, when the bumperelement 67 engages an obstruction it is pushed inwardly against theforce of the spring 73. This moves the rod 68 linearly so that the cam71 moves the actuator 74 of the switch 72, thereby closing the switch72. This, in turn, energizes the solenoid 49 that causes the brakeactuator 50 to apply the brakes. It is preferred to use the latchingrelay 57 with the arrangement of FIG. 7 because the cam 71 may pass bythe switch actuator 74, thereby releasing the switch plunger 74 as therod 68 is moved inwardly, or may be returned to its original position bythe spring 73 to also release the plunger. With the latching relay inthe circuit the brakes will remain applied.

In the embodiment of FIG. 8, the bumper 76 replaces the conventionalbumper at the forward or rearward end of a vehicle 77. The bumper 76 isconstructed of a flexible material such as Butyl rubber defining ahollow chamber 78 within it. A switch 79 is located on the rigid innerplate 80 to which the ends of the bumper are connected. The switch 79 isa normally open pressure-operated switch, responsive to the increases inpressure within the chamber 78. The switch 79 is connected to a circuitcomparable to that of FIG. 4 or FIG. 5 (without the tilt switch 43),replacing the switch 40 of that circuit. Normally, pressure ismaintained in the chamber 78 to assure that the bumper maintains itsshape. This pressure is less than that required to close the switch 79.However, when an obstruction is encountered, the bumper is compressed,raising the pressure within the chamber 78 sufficiently to cause theswitch 79 to close, thereby to actuate the brakes as described above. Inthe event of loss of air from the chamber 78, it can be pressurizedthrough a valve 81, similar to a tire valve. A relief valve 82 protectsagainst damage from overpressurization as might otherwise occur from asevere impact.

In the arrangement of FIG. 9, the bumper is mounted on a deflectableelement which bends under impact to complete the circuit to the brakeactuating solenoid. In this construction the bumper 83 is mounted on arod 84 that is supported by brackets 85 and 86 by insulating grommets 87and 88 through which it extends. A plate 89 carries the brackets 85 and86 and provides a means for attachment to the vehicle. Between thebrackets 85 and 86 is an additional bracket 90 carrying an annularconductor 91 which is of larger internal diameter than the externaldiameter of the rod 84. When the bumper 83 encounters an obstruction,the rod 84 bends as a column, causing its central portion to move to oneside to engage the conductor 91. The rod 84 and conductor 91 are wiredinto the circuit of the brake-actuating solenoid such that thiscompletes the circuit to the solenoid, thereby applying the brakes.

The rod 84 preferably is made in two sections 92 and 93 interconnectedby a stiff compression spring 94. In the event of a severe impact thespring 94 will deflect to prevent damage to the bumper assembly.

In some instances it is preferred to use no bumper element at all and toassure that the vehicle can be backed up only when a man is stationed atthe rearward end of the truck to observe its movement as it backs. Thisarrangement is shown in FIG. 10 in which there is a switch 95 in serieswith the ignition switch 46 and the transmission reverse switch 47, aswell as the brake actuating solenoid 49. The switch 43 also is includedin the event that the vehicle is a dump truck, but is omitted otherwise.The switch 95 is normally closed so that when the ignition switch is onand the truck is placed in reverse gear the circuit is complete to thesolenoid 49, thereby locking the brakes and preventing reverse movement.

The switch 95 is located at the rearward end of the vehicle and can beopened by having its plunger 96 depressed by a man stationed at thatlocation. Thus, it requires two men to back the vehicle with one walkingbeside it holding the plunger 96 depressed so as to open the switch 95and de-energize the solenoid 49 to release the brakes. In the event thatan obstruction is observed at the rearward end of the vehicle, theplunger 96 merely is released to close the switch 92, instantly lockingthe brakes and avoiding damage or injury. The vehicle can be stoppedbefore it even reaches the obstruction. The system is a fail-safe onebecause if the man should happen to stumble and fall or to release theplunger 96 for any other reason, the switch 95 will close and stop thevehicle.

In lieu of being normally closed, the switch 95 may be normally open, inwhich event the plunger 96 is depressed to complete the circuit to thesolenoid 49 for applying the brakes. This lacks the fail-safe feature ofthe system utilizing a normally closed switch, but makes backing thevehicle a simpler operation.

The brake actuating arrangements described above may be controlled byfluid systems rather than the electrical systems shown. Fluid controlscan perform all of the functions of the electrical controls and in someinstances may be preferred. Pneumatic controls are particularlyattractive in view of the source of compressed air normally existing ontrucks, with an adequate oversupply for controlling the braking systemof this invention. Hydraulic controls also are feasible. A latchingmeans may be incorporated in any of the systems set forth, whetherelectrical or fluid controls are used. The same holds true for thecorrelation of the control with the gear selector of the vehicle.

The foregoing detailed description is to be clearly understood as givenby way of illustration and example only, the spirit and scope of thisinvention being limited solely by the appended claims.

We claim:
 1. In combination with a vehicle having brakes, a steeringwheel, gas pedal, and a reverse gear which are operated at a normaldriver's location, a safety device for applying the brakes of saidvehicle comprising:brake applying means; and means for preventingoperation of said brake applying means, including manually operablecontrol means engageable at a second location sufficiently toward therearward portion of said vehicle so as to require a person located nearsaid second location and able to view obstacles behind said vehicle tooperate said manually operable control means, such obstacles not beingvisible from said normal driving location, said operable control meansnot engageable by an operator at said normal driver's location, saidmanually operable control means selectively preventing said vehicle frombacking up.
 2. A device as recited in claim 1 wherein said brakeapplying means comprises:a brake actuator for applying said brakes;circuit means for causing actuation of said brake actuator when saidvehicle is in reverse gear; wherein said means for preventing operationof said brake applying means comprises a normally closed switch, saidclosure energizing the brake actuator; and wherein said manuallyoperable control means comprises an actuating member engageable from theexterior of said vehicle for holding said switch in an open positiononly when said actuating member is so engaged.
 3. A device as recited inclaim 1 wherein said brake applying means comprises a brake actuator forapplying said brakes and circuit means for causing the actuation of saidbrake actuator when said vehicle is in reverse gear, and wherein saidmeans for preventing operation of said brake applying means comprises anormally open switch which when closed energizes the brake actuator andwherein said manually operable control means comprises an actuatingmember engageable from the exterior of the vehicle for closing saidswitch when said actuating member is so engaged.